Hippomanes ( greek ἱππομανές) are brownish or olive-greenish, elastic formations that arise physiologically in mares during pregnancy.

Formation

The up to fist-sized hippomanes are either attached to the

allantois The allantois (plural ''allantoides'' or ''allantoises'') is a hollow sac-like structure filled with clear fluid that forms part of a developing amniote's conceptus (which consists of all embryonic and extraembryonic tissues). It helps the embryo ...

membrane or swim freely in the allantoic fluid. Occasionally such formations also occur in ruminants (cows, sheep, goat) and

pig The pig (''Sus domesticus''), often called swine, hog, or domestic pig when distinguishing from other members of the genus '' Sus'', is an omnivorous, domesticated, even-toed, hoofed mammal. It is variously considered a subspecies of ''Sus s ...

s. Similar formations have also been found in sea-cow, lemur and

hippopotamus The hippopotamus ( ; : hippopotamuses or hippopotami; ''Hippopotamus amphibius''), also called the hippo, common hippopotamus, or river hippopotamus, is a large semiaquatic mammal native to sub-Saharan Africa. It is one of only two extan ...

, but the objects found in the

amnion The amnion is a membrane that closely covers the human and various other embryos when first formed. It fills with amniotic fluid, which causes the amnion to expand and become the amniotic sac that provides a protective environment for the develo ...

and

are distinguishable. This has caused the confusion over the word "hippomanes" in scientific literature, with propositions to use it only for objects found in Equidae pregnancies. Hippomanes arise from unconsumed and thickened nutrient fluid (histiotrophe) of the placenta, in concentric layers around the centre of allantoic calculi of tissue debris. The chemical composition is different to amniotic fluid, which along with the insolubility suggests that it's not a result of a simple precipitation process, but a denatured mucoprotein complex. Hippomanes first appears in pregnant horses and zebras ca. 85 days from conception, earlier there being small white flecks of tissue debris instead. The changes in hippomanes color correspond to changes in color of allantoic fluid. They are often surrounded by shed cells.

History

Hippomanes was first named and described in Ancient Greece, with the name literally meaning "horse madness". It was used as an aphrodisiac in

Ancient period Ancient history is a time period from the beginning of writing and recorded human history to as far as late antiquity. The span of recorded history is roughly 5,000 years, beginning with the Sumerian cuneiform script. Ancient history cov ...

. One of the first written mentions is Aristotle describing the hippomanes circa 350BC. According to

Pliny the Elder Gaius Plinius Secundus (AD 23/2479), called Pliny the Elder (), was a Roman author, naturalist and natural philosopher, and naval and army commander of the early Roman Empire, and a friend of the emperor Vespasian. He wrote the encyclopedic '' ...

, the Hippomanes, which are said to be found as tough bodies on the forehead of the newborn foal, are eaten by the mare immediately after birth. If the mare was prevented from doing so, she would feel no affection for the foal and refuse to feed it, which is why it was believed that the power of love was concentrated in the hippomanes. The vulval discharge from the mare in

oestrus The estrous cycle (, originally ) is the set of recurring physiological changes that are induced by reproductive hormones in most mammalian therian females. Estrous cycles start after sexual maturity in females and are interrupted by anestrous ...

was also referred to as Hippomanes in antiquity and was used equally for love potions and love spells. In a Greek mythology tale, Glaucus, the son of Sisyphus, is devoured by his horses at the funeral games for Pelias, the father of Acastus, during the chariot race, because

Aphrodite Aphrodite ( ; grc-gre, Ἀφροδίτη, Aphrodítē; , , ) is an ancient Greek goddess associated with love, lust, beauty, pleasure, passion, and procreation. She was syncretized with the Roman goddess . Aphrodite's major symbols include ...

had driven them wild with Hippomanes. Later hippomanes has been described and used by

homeopaths Homeopathy or homoeopathy is a pseudoscientific system of alternative medicine. It was conceived in 1796 by the German physician Samuel Hahnemann. Its practitioners, called homeopaths, believe that a substance that causes symptoms of a dise ...

.{{Cite web, title=Hippomanes. from Materia Medica by John Henry Clarke. Homeopathy., url=https://www.materiamedica.info/en/materia-medica/john-henry-clarke/hippomanes, access-date=2021-07-27, website=www.materiamedica.info A hippomane is commonly referred to among horsemen as 'foal's bread'. Its appearance at the birth of a foal (sometimes in its mouth) is regarded as a symbol of good luck. When dried, a 'foal's bread' takes the shape of a tough, leathery heart. See

Foal's Bread ''Foal's Bread'' is a 2011 novel by Australian author Gillian Mears. It was the winner of the 2012 ALS Gold Medal, the Age Book of the Year for Fiction, the Prime Minister's Literary Award for Fiction, and the Victorian Premier's Literary Award f ...

References

Horse anatomy